Urgent safety recommendations have been issued over Boeing 737 aircraft by the US National Transportation Safety Board (NTSB), which warns dozens of airlines may be operating planes with faulty parts.
The NTSB issued an update on Monday after warning last week about the potential for a jammed rudder control system on some 737s.
It follows an NTSB investigation into an incident on 6 February this year in which the rudder pedals on a United Airlines Boeing 737-8 were ‘stuck’ in neutral position during the landing rollout at Newark Liberty International Airport.
The captain was able to control the aircraft’s direction and there were no injuries to passengers or damage to the plane. However, investigators discovered ‘a sealed bearing was incorrectly assembled during production of the actuators, leaving the unsealed side more susceptible to moisture that can freeze and limit rudder system movement’.
The NTSB said: “The rudder rollout guidance actuator, which is installed in the tail of some B-737NG and 737MAX airplanes, is designed to control the rudder’s movement during category IIIB approach, landing and rollout operations. Although it is not used in non-precision landings, the actuator remains mechanically engaged with the rudder system.”
As a result, supplier Collins Aerospace said more than 353 actuators it had delivered to Boeing since February 2017 were affected.
On Monday, the NTSB said 271 impacted parts may be installed on aircraft in service operated by at least 40 foreign carriers and 16 US-registered aircraft. Up to 75 may have been installed afterwards.
Neither the NTSB nor the US Federal Aviation Administration (FAA) have identified the carriers that may be using the parts. One of the airlines is All Nippon Airways, which told Reuters it was in the process of removing the parts, but added it had no impact on operations and was assessing how many planes were impacted.
Japan Airlines, China Airlines and Ryanair said their 737 aircraft were not affected. United said the rudder control parts the NTSB has warned about were in use in only nine of its 737 aircraft originally built for other airlines and the components have all now been removed.
NTSB Chair Jennifer Homendy said in a letter to FAA Administrator Mike Whitaker the NTSB was concerned ‘of the possibility that other airlines are unaware of the presence of these actuators on their 737 airplanes’.
The NTSB also said on Monday it had learned two foreign operators suffered similar incidents in 2019 involving rollout guidance actuators, Reuters added.
